In a guide rail attaching structure for a sliding door and a refrigerator using the same, the structure includes a support member coupled to an inner plate of a door of a refrigerator main body and having support coupling portions, and a pair of guide rails each having a guide rail coupling portion coupled to the corresponding support coupling portion, and slidable with respect to the refrigerator main body, wherein the support coupling portion and the corresponding guide rail coupling portion are coupled to each other by a hinge, whereby a force applied to the guide rail can be minimized to prevent warping of the guide rail even if the sliding door is open in any direction.